Open Project: Cardi Belt – Marcus Tang



As a forgettable person, I usually tend to lose day-to-day objects and spend quite some time trying to find them, such as my whole wallet left at my workplace I found out once I got home that my keys were attached to it. For the sake of losing things without realizing it. I would create a wearable that could give out a reminder when I lose the object. While not trying to reach for complicated mechanisms such as Bluetooth tracking (just like apple tags), the objective was to do a warning before really losing it.


Concept: (Idea and what are you creating)


The concept for the piece would be a cardholder with an alarm feature. Using a simple conductive fabric switch as the main trigger. After pulling out the card, the user has to put the card back within the given time (40 seconds), or else the alarm will go off (with a tiny light show!). 




To make the cardholder wearable, I put leather strips at the back of the cardholder so it could connect any wearables that have a strap to hold on to. With the minimalistic design, this prototype only carries out one mission which is to safely secure your card.



Circuit sewing was done after drawing the diagram on the felt fabric. the felt fabric was separated into two layers and the trigger mechanism is by removing the card and making those two conduct together hence activating the alarm countdown sequence. 




For the Materials, I mainly use felt fabric and faux leather for making the prototype. I used felt to be the canvas when sewing with the conductive threads and drawing the circuit diagram with a Sharpe. Then it was wrapped into a popsicle panel that I made to make the whole structure more steady and wouldn’t collapse. At last, The whole layer is sewed and wrapped in faux leather for a wallet aesthetic and a bit of insulation to the conductive layers. 




For the coding part, I made a one-time code that could be reset manually by using the reset button. First, the code will go for a 40 seconds countdown after the trigger is activated which I think is a reasonable time for you to type the 4-digit code and select the tip amount. If the card is not put back manually and reset by the user. The alarms will go off.




Process (Including ideation drawings, images of the work in progress, and videos of the different steps)

First, I made an idea sketch up on what I would like the prototype to look like.


After the basic sketch-up is done, I started to make hardback support by stacking up wooden popsicle together.


Then, I use felt fabric to be the base canvas for the circuit and draw the circuit layout with a sharpie. Hence connecting everything together.


Moreover, After the second layer of the felt fabric is done. I sewed all the felt fabric along with the CPX with non-conductive threads.


The design was reduced to one card slot due to the short circuit issue, that happened on the first felt trial, to make sure it works I stayed with one card slot instead.


Eventually, the prototype is wrapped in faux leather and sewed together.



Final Project Images (With the wearable being worn!)






Parts List

  1. Conductive threads
  2. Felt
  3. Scissors
  4. Faux leather
  5. Non-conductive thread
  6. CPX
  7. sewing kit
  8. Popsicle sticks
  9. Sharpie



Circuit Diagram:


(Initial idea with 3 card slots)

Reflections & Next Steps :

For the design structure, it could be a more compact and tight fit. Besides, A transparent insulation layer could be placed on top of the CPX as a protective layer. Moreover, Since the prototype carries out a simplistic mission, more card slots could be made maximizing the capability of the CPX can do. For the next steps, I would be working on more sewing techniques to get a better results outcome. Also, I would get custom reset switches instead of relying on the CPX. At last, the most important part is about portability, I would personally fit a 500mAh 3.7 v battery to the CPX so there will be no wires hanging around


Resources & Related Works (cited in APA)


Google. (n.d.). Jacquard by Google – Home. Google. Retrieved April 13, 2022, from

(Simplistic design references and the compatibility with other wearables)


Ekster: Time-saving carry essentials. Ekster® | Trackable, Smart Wallet for Men. (n.d.). Retrieved April 17, 2022, from 

(Overall design references)

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